How to Force Open a Casement Window

Painted casement windows can stick shut.
Painted casement windows can stick shut. (Image: Jupiterimages/ Images)

After trying unsuccessfully to open a stuck casement window, you might think that nothing short of breaking it will do the trick. Don’t grab a rock just yet, though. A casement window can stick shut for different reasons. By identifying and treating all those usual suspects, you greatly improve the odds of transforming it into a functional window. A few additional measures will also help you prevent it from sticking again after you close it.

Things You'll Need

  • Serrated blade
  • Hammer
  • Block of wood
  • Towel
  • Putty knives
  • Lubricant
  • Sandpaper
  • Varnish
  • Wax candle

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Wait for cooler weather if the window became stuck during high heat. It may open more readily then, as humidity can cause swelling in the trim.

Remove any dried paint from the gap between the sash and frame by sawing or tapping through it with a serrated blade. Tap the blade’s handle with a hammer to get into the space. Repeat this on the exterior side.

Wrap a small block of wood in a towel and hold it against the sash. Tap the covered block with a hammer, and continue this motion around the window’s edges. This helps loosen any remaining debris or dried paint lodged in the space.

Repeat the block and hammer process along the window stop, which can bind against the sash and prevent it from moving. Remove and reposition the stop if it’s misaligned.

Place the head of a putty knife in the lower section of the crevice between the sash and frame on the opposite side of the hinges. Bend the handle of the putty knife to gently pry it open. Continue this motion up to the top of the window, and repeat it along the top and bottom edges. Use two putty knives simultaneously for additional leverage. This breaks the seal of any sticky substances in the space and can help you move stiff hinges.

Spray the hinges with lubricant and tighten any loose screws. Remove and replace the hinges if they’re heavily rusted.

Remove the crank's cover and lubricate the inner gears to reduce or prevent sticking as they turn.

Sand the sections where the sash and frame meet once it opens to remove excess paint and rough wood, and apply a varnish to seal it. Rub those sections with a wax candle to further prevent sticking.


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